1. Field of the Invention
The present invention relates to a joint structure for extruded members for the joint with the end portion of a first extruded member butted against the side surface of a second extruded member, and a mounting structure for a traction hook for mounting a traction hook on the front surface of a bumper beam being the extruded member.
2. Description of the Related Art
Conventionally, there have been automobiles comprising a frame made of an aluminum alloy extruded member. According to the frame structure, extruded members need to be jointed at a junction of the members as disclosed in, for example, JPA-7-80570. Various joint methods for the extruded members have been proposed, depending on the part. Examples thereof are presented below.
For example, members are butted and welded in a tail gate part, between a side sill and a front floor cross member, or in a door upper sash. Members are welded each to a cast part disposed therebetween, between a rear floor cross member and a rear frame, or between a rear frame and a side sill. Extruded members are welded with respect to a connecting part press worked like a waffle, covering over the joint part of both members, between a roof rail and a front pillar, or between a pillar lower and a front pillar.
However, according to the coupling by welding as mentioned in the examples, a problem is involved in that the strength of the material is deteriorated at the welded part with respect to the extruded members due to the thermal effect. Moreover, in the case the welding structure is used for a portion to be repaired frequently so as to be replaced by a repair part, the repair cost is soared so as to increase the burden on the user. Furthermore, in the case of those using a connecting part press worked like a waffle, since the extruded members are jointed only on the surface, and thus a problem is involved in that it is difficult to improve the coupling strength with respect to the extruded members, using a small connecting part.
In addition, conventionally, there have been traction hooks provided on the front and rear end portions of an automobile for the traction at the time of breakdown of the automobile, or the like. Examples thereof include those having a plate elongating downward, provided on the front end portion of a front side frame via a bracket, with a hook hole formed in the plate so as to serve as a traction hook. According to the structure, a problem is involved in that the weight is increased due to bulkiness of the bracket and the plate.
In contrast, those comprising a frame made of an aluminum alloy material have been provided in order to further realize the light weight of the automobile. Among these car bodies, for example, JP-A-5-8758 discloses those having a bumper beam also comprising an aluminum alloy extruded member.
However, in the case of mounting a traction hook to the aluminum alloy bumper beam, a steel material cannot be welded thereto. Also in the case of the aluminum alloy material, a problem arises in difficulty in welding, and a high cost.
Moreover, in the case of forming a traction hook with an eye bolt-like shape, although the traction hook can be mounted on the bumper beam by screwing, since the screw hole strength is low in the case of those made from the aluminum alloy as mentioned above, a problem is involved in that the traction hook cannot be mounted directly on the bumper beam by screwing.
In view of the above problems, an object of the invention is to facilitate detachment and assembly in replacing parts as well as to realize the compactness in the joint structure for extruded members. Further, another object of the invention is to realize a mounting structure for a traction hook, capable of providing a sufficient strength even in the case an aluminum alloy bumper beam is used as well as capable of restraining the weight increase.
To solve the above object, according to a first aspect of the invention, there is provided a joint structure for extruded members for the joint with the end portion of a first extruded member butted against the side surface of a second extruded member, wherein the extruded members are jointed with each other via a joint member coupled to the end portion and the side surface by fastening means.
According to the configuration, since the joint with the extruded members butted with each other is executed with the fastening means, the thermal effect with respect to the extruded members in the joint by welding can be eliminated as well as detachment and assembly can be facilitated in replacing the parts.
Moreover, since the joint member comprises a first coupling piece to be superimposed on a part of the end portion, and a second coupling piece to be superimposed on a part of the side surface, with each of the coupling pieces coupled with the corresponding end portion and side surface by the fastening means, the coupling efficiency can be improved according to coupling with the coupling pieces of the joint member inserted and superimposed in the end portion of the other extruded member as well as the amount of projection of the joint member outward from the extruded members restrained at a minimum level.
Further, according to the second aspect of the invention, there is provided amounting structure for a traction hook for mounting a traction hook on the front surface of a bumper beam, wherein an operation hole for allowing the operation from the front surface side of the bumper beam at the time of coupling a frame component member by screwing onto the rear surface of a bumper beam is provided on the front surface of the bumper beam, and a metal fixture for mounting the traction hook is coupled with the bumper beam by screwing so as to close the operation hole.
According to the configuration, since the metal fixture for mounting the traction hook is provided so as to close the frame component member coupling operation hole provided in the front bumper beam by screwing at the time of mounting the traction hook onto the front bumper beam comprising an aluminum alloy extruded member for further achieving the light weight of the car body, the front bumper beam is not applied with the thermal effect by welding. Furthermore, since the traction hook is mounted directly on the metal fixture, a bracket is not required, and thus the light weight and the low cost can further be achieved. Moreover, since the operation hole can be closed by the metal fixture, the rigidity of the portion can be improved.
Furthermore, since a bolt part is provided in the traction hook as well as a hook mounting nut for screwing the bolt part therein is provided in the metal fixture, with the hook mounting nut provided facing outward from the operation hole, in the case the operation hole for coupling the front bumper beam and the frame component member by screwing is provided in the front bumper beam, the operation hole can be utilized preferably as the traction hook mounting portion.